<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0,maximum-scale=1.0,minimum-scale=1.0,user-scalable=no">
    <title>Document1</title>
    <style type='text/css'>
        * {
            margin: 0;
            padding: 0;
        }

        html,
        body {
            height: 100%;
        }

        .flex {
            display: flex;
        }

        .flex-row {
            flex-direction: row;
            justify-content: space-around;
            align-items: center;
        }

        .flex-column {
            flex-direction: column;
            justify-content: flex-start;
            align-items: center;
        }

        body {
            overflow: auto;
            background: #fff;
        }

        .title {
            width: 920px;
            padding: 30px;
            align-items: flex-end;
        }

        .title h1 {
            padding-bottom: 20px;
            font-size: 38px;
            color: #ffffff;
            text-shadow: 0 1px 3px #222222;
        }

        .title p {
            font-size: 18px;
            color: #f5f5f5;
            text-shadow: 0 1px 3px #565656;
        }

        .wrap {
            width: 1220px;
        }

        .wrap .reference {
            position: relative;
            padding: 10px;
            background-color: rgba(255, 255, 255, 0);
            border-radius: 10px;
            box-shadow: 0 0 20px #a1a19f;
        }

        .wrap .reference img.face {
            display: block;
            width: 320px;
            height: auto;
            border-radius: 10px;
        }

        .wrap .reference img.toggle {
            position: absolute;
            right: 10px;
            top: 10px;
            width: 50px;
            height: 50px;
        }

        .wrap .scan video {
            background-color: rgba(0, 0, 0, .8);
            border-radius: 10px;
        }

        .wrap .control {
            justify-content: space-around;
            height: 456px;
            padding: 0 20px;
        }

        .wrap .control p {
            width: 160px;
            height: 60px;
            background-color: #f9f9f9;
            text-align: center;
            line-height: 60px;
            color: #ffffff;
            font-size: 24px;
            border-radius: 8px;
            cursor: pointer;
            box-shadow: -8px -8px 150px -8px #b2b3b5 inset, 0 0 5px #222222;
            text-shadow: 0 0 1px #222222;
            transition: .5s;
        }

        .wrap .control p:hover {
            box-shadow: -8px -8px 150px -8px #50c4f1 inset, 0 0 5px #ffffff;
        }

        .wrap .scan {
            position: relative;
            overflow: hidden;
        }

        .wrap .scan .strainer {
            position: absolute;
            top: 10px;
            width: 320px;
            z-index: 999;
            height: 3px;
        }

        .wrap .scan .capture {
            width: 320px;
            height: 456px;
        }

        .wrap .scan .strainer.on {
            background: linear-gradient(to left, transparent, #0bffb2, transparent);
            animation: scan 1s linear infinite;
        }

        @keyframes scan {
            0% {
                top: 10px;
            }
            50% {
                top: 456px;
            }
            100% {
                top: 10px;
            }
        }
    </style>
    <script src="https://bluelotos.gitee.io/lib/vconsole/dist/vconsole.min.js"></script>
</head>

<body>
    <!-- https://segmentfault.com/a/1190000014222822 -->
    <div class="title flex flex-column">
    </div>
    <div class="wrap flex flex-row">
        <div class="control flex flex-column">
            <p class="open">开启摄像头</p>
            <p class="recognition">显示到Canvas</p>
            <p class="close">关闭摄像头</p>
        </div>
        <div class="scan reference">
            <div class="strainer"></div>
            <video class="capture" width="320" height="456" src=""></video>
        </div>
        <div id="imgwrap"></div>
    </div>

    <script type="text/javascript">
    var vConsole = new VConsole();
        var buffer;
        var oCapture = document.querySelector(".capture"),
            open = document.querySelector(".open"),
            recognition = document.querySelector(".recognition"),
            close = document.querySelector(".close");
        var control = document.querySelector(".control");
        let currentStream;
        window.navigator.getUserMedia = navigator.getUserMedia || navigator.webKitGetUserMedia || navigator.mozGetUserMedia ||
            navigator.msGetUserMedia;

        function invokingCarera() {
            if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
                navigator.mediaDevices.getUserMedia({
                        'audio': true,
                        'video': {
                            'facingMode': { exact: "environment" }
                        } //调用前置摄像头，后置摄像头使用video: { facingMode: { exact: "environment" } }
                    })
                    .then(function (mediaStream) {
                        console.log(555);
                        currentStream = mediaStream;
                        getVideoStream(mediaStream)
                    })
                    .catch(function (error) {
                        console.log(666);
                        console.log(error)
                    })
            } else if (navigator.getUserMedia) {
                navigator.getUserMedia({
                    'video': true,
                    'audio': true
                }, getVideoStream, getFail)
            } else {
                alert('不支持摄像头调用！')
            }
        }
        //调用成功
        function getVideoStream(stream) {
            buffer = stream;
            if (oCapture.mozSrcObject !== undefined) {
                oCapture.mozSrcObject = buffer;
            } else {
                oCapture.src = window.URL && window.URL.createObjectURL(buffer);
            }
            oCapture.play();
        }

        function getFail() {

        }
        recognition.onclick = function () {

        }
        control.addEventListener('click', function (e) {
            e = e || window.event;
            var className = e.target.className;
            switch (className) {
                case 'open':
                    invokingCarera();
                    break;
                case 'close':
                    closeCamera();
                    break;
                case 'recognition':
                    screenShot();
                    break;
                default:
                    break;
            }
        })
        function stopMediaTracks(stream) {
            stream.getTracks().forEach(track => {
                track.stop();
            });
        }
        function closeCamera() {
            buffer && buffer.getTracks()[1].stop(); //关闭摄像头
            if (typeof currentStream !== 'undefined') {
                stopMediaTracks(currentStream);
            }
        }
        window.requestAnimFrame = (function () {
            return window.requestAnimationFrame ||
                window.webkitRequestAnimationFrame ||
                window.mozRequestAnimationFrame ||
                function (callback) {
                    window.setTimeout(callback, 1000 / 60);
                };
        })();

        function screenShot() {
            var canvas = document.createElement('canvas');
            canvas.width = 320, canvas.height = 456;
            document.querySelector("#imgwrap").innerHTML = "";
            document.querySelector("#imgwrap").appendChild(canvas);
            var ctx = canvas.getContext('2d');

            function drawVideo() {
                ctx.drawImage(oCapture, 0, 0, 320, 456);
                ctx.font = "30px sans-serif";
                ctx.fillStyle = "blue";
                ctx.fillText("请眨眼", 50, 50);
                requestAnimationFrame(drawVideo);
            }
            window.requestAnimationFrame(drawVideo);
        }
    </script>
</body>

</html>